1. Field of the Invention
The disclosure relates to a liquid crystal display (LCD) driver integrated circuit package and a chip on glass type LCD device using the same, and more particularly to an LCD driver integrated circuit package and a chip on glass type LCD device capable of decreasing bonding failures that occur during a mounting process for an LCD device.
2. Description of the Prior Art
Generally, an LCD device is a flat panel display device for displaying characters, images and motion pictures by means of liquid crystal.
The LCD device includes an LCD panel for controlling the image that is generated, a light supplying device for providing light to the LCD and a driver module for driving the LCD panel to display desired images. The LCD panel is composed of a TFT (Thin Film Transistor) substrate, the liquid crystal and a color filter substrate.
The TFT substrate includes a glass substrate, TFTs arranged in a matrix on the glass substrate, gate lines and data lines for driving the TFT, and a transparent pixel electrode to which a voltage signal from the TFT is applied.
The color filter substrate includes a glass substrate, a color filter arranged in a matrix on the glass substrate to face the pixel electrode of the TFT substrate, and a common electrode formed on the whole glass substrate to cover the color filter.
The TFT substrate and the color filter substrate are positioned so that the pixel electrode is aligned with the color filter and a gap is formed between the TFT substrate and the color filter substrate. This gap is filled with a liquid crystal layer of a predetermined thickness.
The driver module provides a driving signal for displaying an image to the TFTs on the TFT substrate. This driver module is comprised of a PCB (Printed circuit board) and a TCP (Tape Carrier Package). The PCB converts an image signal input from a data processing device into a driving signal so that the driving signal is recognized by the LCD device.
The TCP is comprised of a base film and a driver IC. The base film is made of a synthetic resin having a thin plate shape, and the driver IC is mounted thereon. The driver IC provides the driving signals from the PCB to the LCD panel at a predetermined time interval. The PCB is bent toward a rear surface of the LCD panel by means of the flexible base film of the TCP.
Recently, an LCD driver integrated circuit package has been recently developed to manufacture a thinner and lighter LCD device. The LCD driver integrated circuit package can be easily mounted on the LCD panel. The LCD device mounted with LCD driver integrated circuit package is referred to as a chip on glass type LCD device.
FIG. 1 shows a schematic view showing a conventional LCD driver integrated circuit package.
Referring to FIG. 1, the LCD driver integrated circuit package 100 is a source driving integrated circuit package mounted on data lines. This LCD driver integrated circuit package 100 includes a driving signal processing module 90, a mold 80, image signal input bumps 70 and driving signal output bumps 60.
The driving signal processing module 90 converts an image signal from a data processing device into a driving signal capable of being recognized by the LCD device. The driving signal processing module 90 includes image signal input pads 92 and driving signal output pads 94. The image signal input pads 92 receives the image signal, and the driving signal output pads 94 output the converted driving signal.
Often, the driving signal output pads 94 and the image signal input pads 92 may not be directly mounted on a data line of the LCD panel and on a signal line of the PCB because the driving signal output pads 94 and the image signal input pads 92 have a narrow width (e.g., in the order of μm) and small dimensions.
For this reason, the conventional driving signal processing module 90 is enclosed by the mold 80, and the driving signal output bumps 60 are formed on the mold 80. The driving signal output bumps 60 have large enough width and dimension to be connected to the LCD panel. The driving signal output bumps 60 are connected to the driving signal output pads 94 through, for example, conductive wires 96. The image signal input bumps 70 are also formed on a surface of the mold 80 along an edge that is opposite the edge on which the driving signal output bumps 60 are formed. The image signal input bumps 70 have large enough width and dimensions to be connected to the signal line of the PCB. The image signal input bumps 70 are connected to the image signal input pads 92 through, for example, conductive wires 98.
FIG. 2 is a cross sectional view cut along a line II—II of FIG. 1
Referring to FIG. 2, the image signal input bumps 70 are connected to conductive patterns 40 of the LCD panel so as to be connected to the PCB via an anisotropic conductive film (ACF) 50. The driving signal output bumps 60 are connected to data lines 30 of the LCD panel via the anisotropic conductive film 50. A transparent substrate 20 supports the conductive patterns 40, as shown.
As shown in FIG. 2, a bonding head (not shown) applies a force (F) to the LCD driver integrated circuit package 100. The driving signal output bumps 60 apply an amplified pressure Pa to the anisotropic conductive film 50 so that the driving signal output bumps 60, the anisotropic conductive film 50 and the data lines 30 are electrically connected with each other.
The force (F) is also applied to the image signal input bumps 70. The image signal input bumps 70 apply pressure Pb to the anisotropic conductive film 50 so that the image signal input bumps 70 the anisotropic conductive film 50 and the conductive patterns 40 are electrically connected with each other.
The chip on glass type LCD device is advantageous in that the dimension, weight and the number of required parts of the LCD device are greatly decreased. However, the chip on glass type LCD device also has limitations owing to characteristics of the chip on glass type LCD device.
Some of the limitations result from the difference between the total area of the image signal input bumps 70 and total areas of the driving signal output bumps 60. When the total area of the image signal input bumps 70 is different from the total area of the image signal output bumps 60, the image signal input bumps 70 and the driving signal output bumps 60 apply different pressures onto the substrate even though an equal force (F) is y applied to the image signal input bumps 70 and the driving signal output bumps 60.
When pressures from the image signal input bumps 70 and the driving signal output bumps are different from each other, for example when the total area of the respective image signal input bumps 70 is larger than the total area of the respective the driving signal output bumps 60, the pressure Pb applied onto the image signal input bumps 70 is smaller than the pressure Pa applied on the driving signal output bumps 60.
When the pressure Pb applied onto the image signal input bumps 70 is smaller than the pressure Pa applied on the driving signal output bumps 60, the driving signal output bumps 60 and the anisotropic conductive film 50 are excessively compressed in some cases. In other cases, the image signal input bumps 70 and the anisotropic conductive film 50 are not compressed sufficiently. This excessive or insufficient compression causes undesirable deteriorations in the electric characteristics, ultimately affecting the displayed image. An LCD driver integrated circuit package that does not suffer from this type of electric deteriorations is needed.